Traces from primordial times

The problem is that DNA sequences change a lot over time. Parts of the DNA may have been wiped away during the passing of the years. Since the protozoan is a very old species, an extra large amount of gene information is required.

"It is often the case with such ancient organisms that features they share in common with other known species have been wiped away from the DNA sequence because of long-term mutations. You can compare it with tarmacing. If you tarmac a road enough times, you will no longer see the cobblestones. Therefore, you have to collect large gene sequences to find common traces from prehistoric times."

Research fellow Sen Zhao was responsible for the extensive, statistical calculations. In order to calculate the family link they have used information from the research group's own Bioportal in cooperation with the high performance computing group at the University of Oslo.

Kamran Shalchian-Tabrizi explains that the tree of life can provide fundamental answers to great evolutionary mysteries. "In order to understand what a species is today, we have to understand how they have changed genetically. The tree of life allows us to explain cellular change processes by connecting the genome and morphology (appearance) with its way of life."

Among other things, Shalchian-Tabrizi wants to use the protozoan to investigate when photosynthesis arose among eukaryote organisms. Photosynthesis takes place in chloroplast. Chloroplasts were originally free-living, blue green bacteria. If the researchers find genetic residues of these bacteria in the protozoan from Ås, this may indicate that photosynthesis arose earlier than supposed.

"There are many likely scenarios, but we still do not know the answer," acknowledges Shalchian-Tabrizi.

The researchers also want to question when other characteristics arose, e.g. mitochondria, which are the energy motors of our cells.

Purifying drinking water in Japan

In recent years researchers have found some apparently matching examples of the protozoan from Ås in Japan and South East Asia. A researcher from Japan arrived in Oslo with a glass of the species solely so that Klaveness could breed them. "We are now going to gene sequence these organisms, because it is not certain that the genes are the same, even if the morphology is similar," says Klaveness. The Japanese hope that the protozoan can be used to purify drinking water by removing toxic, blue green bacteria.

Still, it is fascinating to imagine a yellow dwarf that is exactly the same mass, temperature and chemical composition as our nearest star. In a recent paper reporting on observations of the star - called HP 56948 - astronomer Jorge Melendez of the University of San Paulo, Brazil, calls it "the best solar twin known to date."

His team combined observations from the Very Large Telescope (VLT), Keck Telescope, and Hobby Eberly Telescope to characterize the star and look for planets. Though fast orbiting large planets weren't found it still begs the question: could HP 56948 have a twin solar system too?

The majority of planetary systems discovered to date make our solar system look like the exception and not the rule. For example, the sun-like star 55 Cancri, only 41 light-years away, has a mix of close-in hot Jupiters, followed by terrestrial planets an then more Jupiters. In some systems the planets are in much more elliptical orbits than found around our sun. Epsilon Eridani for example has a planet that swings as close to the star as Venus is from our sun, and then climbs out to the orbital radius of Jupiter.

The good news is that astronomers have not detected the short-period wobble of HP 56948 that would indicate a hot Jupiter was tugging on it. This leaves the inner few million miles around the star safe territory for the presence of one or more terrestrial planets. Earth-mass worlds would pull so weakly on the star that they have not yet been detected. But the chemical composition of HP 56548 has unusual amounts of aluminum, calcium, magnesium, and silicon - by the same ratio as our sun has. In our solar system these elements are found locked away in interplanetary dust, meteorites and rocky planets like Earth.

This means terrestrial planets could exist around HP 56548. In fact, there is a reasonable chance that the star's planetary system has a solar system architecture with the massive outer worlds staying beyond the "frost line" where ices condense to form bloated worlds. And, a family of terrestrial planets huddled close to the star.

Simply put, the nearby presence of a twin star potentially offers a fascinating experiment in parallel evolution. Assuming that HP 56548 has at least one inhabitable planet, has life arisen and successfully evolved to higher forms over 4 billion years? If not, why not?

If 4 billion years is the typical time for the emergence of intelligent beings, then there is a civilization now orbiting HP 56548. If we dare to extrapolate even further, a technological civilization should have developed astronomy, which is at the root of modern physics. Their astronomers should have located our sun as easily as we found their star. They then might have been compelled to undertake a program of both monitoring and transmitting radio message to our solar system.

That said, it would not be surprising if SETI observations of the star came up empty handed. The system may not have an Earth-sized planet in its habitable zone. Even if there is one it may not be Earth-like with oceans and plate tectonics. And, even if there is a world flourishing with multi-cellular life, it may not have progressed to an intelligent species. Or, it has a civilization but it is not as technologically advanced as ours.

Keep in mind that any alien astronomers on such a planet would be studying Earth as it appeared in the early 1800s. That information, encoded in light, is just arriving at HP 56948 now. Our radio and television signal leaking into space won't reach the star for another 130 years. In the absence of such an electromagnetic signature extraterrestrials may overlook Earth and scout elsewhere. They nevertheless would speculate, as we are, whether our sun offers and abode for intelligent life. But the quarantine imposed by the physics of time and space keeps us forever apart.

ScienceDaily- Scientists at Duke University Medical Center have shown the ability to turn scar tissue that forms after a heart attack into heart muscle cells using a new process that eliminates the need for stem cell transplant.

The study, published online April 26 in the journal Circulation Research, used molecules called microRNAs to trigger the cardiac tissue conversion in a lab dish and, for the first time, in a living mouse, demonstrating the potential of a simpler process for tissue regeneration.

If additional studies confirm the approach in human cells, it could lead to a new way for treating many of the 23 million people worldwide who suffer heart failure, which is often caused by scar tissue that develops after a heart attack. The approach could also have benefit beyond heart disease.

"This is a significant finding with many therapeutic implications," said Victor J. Dzau, MD, a senior author on the study who is James B. Duke professor of medicine and chancellor of health affairs at Duke University. "If you can do this in the heart, you can do it in the brain, the kidneys, and other tissues. This is a whole new way of regenerating tissue."

To initiate the regeneration, Dzau's team at Duke used microRNAs, which are molecules that serve as master regulators controlling the activity of multiple genes. Tailored in a specific combination, the microRNAs were delivered into scar tissue cells called fibroblasts, which develop after a heart attack and impair the organ's ability to pump blood. Once deployed, the microRNAs reprogrammed fibroblasts to become cells resembling the cardiomyocytes that make up heart muscle. The Duke team not only proved this concept in the laboratory, but also demonstrated that the cell conversion could occur inside the body of a mouse -- a major requirement for regenerative medicine to become a potential therapy.

"This is one of the exciting things about our study," said Maria Mirotsou, PhD, assistant professor of cardiology at Duke and a senior author of the study. "We were able to achieve this tissue conversion in the heart with these microRNAs, which may be more practical for direct delivery into cells and allow for possible development of therapies without using genetic methods or transplantation of stem cells."

The researchers said using microRNA for tissue regeneration has several potential advantages over genetic methods or transplantation of stem cells, which have been difficult to manage inside the body. Notably, the microRNA process eliminates technical problems such as genetic alterations, while also avoiding the ethical dilemmas posed by stem cells. "It's an exciting stage for reprogramming science," said Tilanthi M. Jayawardena, PhD, first author of the study. "It's a very young field, and we're all learning what it means to switch a cell's fate. We believe we've uncovered a way for it to be done, and that it has a lot of potential."

The approach will now be tested in larger animals. Dzau said therapies could be developed within a decade if additional studies advance in larger animals and humans. "We have proven the concept," Dzau said. "This is the very early stage, and we have only shown that is it doable in an animal model. Although that's a very big step, we're not there yet for humans."

In addition to Dzau, Mirotsou and Jayawardena, study authors include: Bakytbek Egemnazarov; Elizabeth A. Finch; Lunan Zhang; Kumar Pandya; J. Alan Payne; Zhiping Zhang; and Paul Rosenberg.

The research team, led by Professor Birger Rasmussen of Curtin University, includes Dr Janet Muhling from The University of Western Australia's Centre for Microscopy, Characterisation and Analysis.

Iron formations are unique sedimentary rocks composed of iron and silica and are unlike any modern rocks, the study noted. Most iron formations were deposited in the oceans before free oxygen first accumulated in Earth's atmosphere about 2.4 billion years ago (the so-called Great Oxidation Event). However, the re-occurrence of major iron formations nearly 500 million years later has been an enduring enigma for geologists.

Major iron formations about 1.9-1.8 billion years old occur in both North America and Australia. However, because the Australian iron formations were thought to be significantly younger than those in North America, it was uncertain whether they provided information about the composition of the global ocean or conditions in a restricted or closed basin. The new study has dated volcanic ash beds in the Australian iron formations, showing that they were deposited at the same time as those in North America.

"These results show that the deposition of iron formations from two different continents was synchronous 1.9 billion years ago and therefore probably reflects the composition of the global ocean," the study said. "The deposition of major iron formations shows a remarkable correlation in time with a short-lived but intense interval of global igneous activity, a possible mantle superplume event, which suggests that processes deep within the Earth radically changed the chemistry of the global ocean."

"We suggest that extensive basaltic magmatism related to the superplume released vast volumes of iron into the global ocean, overwhelming the supply of oxygen and promoting the deposition of iron formations across the world," Dr Muhling said. "The equally dramatic disappearance of iron formations some 40 million years later can be explained as a consequence of rapidly waning igneous (volcanic) activity that allowed the ocean to become dominated by seawater oxidants once more.

"Our findings not only explain the sudden appearance and disappearance of iron formations circa 1.9 billion years ago, but also provide an explanation for the preservation of an oxygen-rich atmosphere above an oxygen-poor ocean. The relationships between the chemistry of the hydrosphere and atmosphere, and deep Earth processes provide insights into significant events in the evolution of the Earth," Dr Muhling said.

Dr Muhling's co-researchers are from Curtin University, the WA Department of Mines and Petroleum's Geological Survey of WA, and the University of Manitoba in Canada. Provided by University of Western Australia

http://bit.ly/KgB7ET

Evolution re-run test to probe life's predictability

A 500-million-year-old bacterial gene got a second chance at evolution this year. The experiment may help biologists understand the extent to which evolution is predictable.

13:32 27 April 2012 by Bob Holmes

Biologists have long wondered whether life would evolve the same way again if we could rewind the tape. Eric Gaucher and Betül Arslan at Georgia Tech University in Atlanta hope to find out.

They focused on EF-Tu, a gene in Escherichia coli that plays a crucial role in protein synthesis. Gaucher had previously worked out what this gene's DNA sequence must have been 500 million years ago, by comparing the sequences of many modern bacteria and reasoning backwards.

Now Arslan has synthesised the ancient gene and inserted it into E. coli in place of the modern version. The bacteria with the old gene grew less than half as fast as usual. Arslan then let eight bacterial lines evolve independently for 1000 generations.

All eight lineages eventually grew faster - a sign that evolution had occurred. When Arslan sequenced their genomes, though, she found that EF-Tu was unchanged. What had evolved - differently in each lineage - were the genes that interact with EF-Tu. She reported the work at NASA's Astrobiology Science Conference 2012 in Atlanta.

The sheer number of interacting genes in protein synthesis means that random mutations are more likely to hit one of EF-Tu's partners than EF-Tu itself. Eventually, though, EF-Tu may begin to evolve - either following the same path it began 500 million years ago or not. The experiment continues.

Step outside any night this week about an hour after sunset and have a look at the western sky. The first thing that will catch your eye is the brilliant planet Venus. Look a little more closely and you'll see that Venus is surrounded by bright stars. The sky map accompanying this story will help you identify them.

Although Venus is always one of the brightest objects in the sky, this week it is at its very brightest. That's because of a combination of circumstances.

The solar system's two innermost planets, Mercury and Venus, go through a series of phases similar to the moon, as they are lit from the side at different angles by the sun. Their apparent size also changes as they move from the far side of the sun to the near side.

Currently Venus is moving toward the Earth, so it is getting larger and brighter. Its phase is also narrowing as it moves in front of the sun, which makes it decrease in brightness. So we've got two opposing forces in action: Getting closer means getting brighter, and a narrowing crescent means getting fainter. This week the two balance out to make Venus as bright as it can possibly be.

Through a telescope this week, Venus will look like a miniature version of a five-day-old moon, except without any mountains, lava seas or craters. The view of Venus through a telescope is often disappointing and surprising; it doesn't seem like something so beautiful to the naked eye should be so bland when magnified.

Despite Venus' somewhat boring appearance, there is a lot going on beneath the planet's clouds. Its dense atmosphere and proximity to the sun make for an exaggerated greenhouse effect. The surface temperature on Venus is a hellish 860 degrees Fahrenheit (460 degrees Celsius). By way of comparison, the melting point of lead is 621 F (327 C).

Over the next few weeks, Venus will continue to approach the Earth, getting larger in size as its crescent continues to narrow. Even if you don't have a telescope, take a look at Venus with binoculars. Soon you will see it as a tiny crescent.

PROVIDENCE, R.I. [Brown University] — Red, green, and blue lasers have become small and cheap enough to find their way into products ranging from BluRay DVD players to fancy pens, but each color is made with different semiconductor materials and by elaborate crystal growth processes. A new prototype technology demonstrates all three of those colors coming from one material. That could open the door to making products, such as high-performance digital displays, that employ a variety of laser colors all at once.

"Today in order to create a laser display with arbitrary colors, from white to shades of pink or teal, you'd need these three separate material systems to come together in the form of three distinct lasers that in no way shape or form would have anything in common," said Arto Nurmikko, professor of engineering at Brown University and senior author of a paper describing the innovation in the journal Nature Nanotechnology. "Now enter a class of materials called semiconductor quantum dots."

The materials in prototype lasers described in the paper are nanometer-sized semiconductor particles called colloidal quantum dots or nanocrystals with an inner core of cadmium and selenium alloy and a coating of zinc, cadmium, and sulfur alloy and a proprietary organic molecular glue. Chemists at QD Vision of Lexington, Mass., synthesize the nanocrystals using a wet chemistry process that allows them to precisely vary the nanocrystal size by varying the production time. Size is all that needs to change to produce different laser light colors: 4.2 nanometer cores produce red light, 3.2 nanometer ones emit green light and 2.5 nanometer ones shine blue. Different sizes would produce other colors along the spectrum.

The cladding and the nanocrystal structure are critical advances beyond previous attempts to make lasers with colloidal quantum dots, said lead author Cuong Dang, a senior research associate and nanophotonics laboratory manager in Nurmikko's group at Brown. Because of their improved quantum mechanical and electrical performance, he said, the coated pyramids require 10 times less pulsed energy or 1,000 times less power to produce laser light than previous attempts at the technology.

Quantum nail polish

When chemists at QDVision brew a batch of colloidal quantum dots for Brown-designed specifications, Dang and Nurmikko get a vial of a viscous liquid that Nurmikko said somewhat resembles nail polish. To make a laser, Dang coats a square of glass — or a variety of other shapes — with the liquid. When the liquid evaporates, what's left on the glass are several densely packed solid, highly ordered layers of the nanocrystals. By sandwiching that glass between two specially prepared mirrors, Dang creates one of the most challenging laser structures, called a vertical-cavity surface-emitting laser. The Brown-led team was the first to make a working VCSEL with colloidal quantum dots.

The nanocrystals' outer coating alloy of zinc, cadmium, sulfur and that molecular glue is important because it reduces an excited electronic state requirement for lasing and protects the nanocrystals from a kind of crosstalk that makes it hard to produce laser light, Nurmikko said. Every batch of colloidal quantum dots has a few defective ones, but normally just a few are enough to interfere with light amplification.

Faced with a high excited electronic state requirement and destructive crosstalk in a densely packed layer, previous groups have needed to pump their dots with a lot of power to push them past a higher threshold for producing light amplification, a core element of any laser. Pumping them intensely, however, gives rise to another problem: an excess of excited electronic states called excitons. When there are too many of these excitons among the quantum dots, energy that could be producing light is instead more likely to be lost as heat, mostly through a phenomenon known as the Auger process.

The nanocrystals' structure and outer cladding reduces destructive crosstalk and lowers the energy needed to get the quantum dots to shine. That reduces the energy required to pump the quantum dot laser and significantly reduces the likelihood of exceeding the level of excitons at which the Auger process drains energy away. In addition, a benefit of the new approach's structure is that the dots can act more quickly, releasing light before Auger process can get started, even in the rare cases when it still does start.

"We have managed to show that it's possible to create not only light, but laser light," Nurmikko said. "In principle, we now have some benefits: using the same chemistry for all colors, producing lasers in a very inexpensive way, relatively speaking, and the ability to apply them to all kinds of surfaces regardless of shape. That makes possible all kinds of device configurations for the future."